Radio frequency transformer



Nov. 18,1930. F. L. cAPPs 1,781,776

RADIOFREQUENCY TRANSFORMER Filed March 10, 1926 zzyl 90 B Volfs l m l l 6 VoHS INVENTOR. BY Emmi; 1?. Kappa A TTORNEYS.

Patented Nov. 18, 1930 FRANK L. CAPPS, OF BRIDGEP ORT, CONNECTICUT RADIO FR'EQUENUY TRANSFORMER Application filed March 10, 1926. Serial No. 93,578.

This invention relates to improvements in radio frequency transformers, tuning coils or the like such as are employed in radio receiving sets.

My invention is equally applicable to a transformer, a tuning coil, a vario coupler and a variometer such as are used in circuits of various styles of radio receiving sets of tuned radio frequency type.

The object of the invention is to produce a transformer whose respective windings of wire form a flat spiral, produced by rolling the wire upon itself in a way so that the successive windings build up and recede from its center, forming an annular compilation of numerous layers of wire from the same continuous strip and to support the same in such annular relation, and further to provide a strip of insulating material therebetween and rolled with the wire. The coil, in this respect being distinguished from the usual forms of coils,'of round wire, which are wound longitudinally of and upon the surface of a cylinder or spool. Another and important object of the invention is to form the metal coil of fiat or ribbon wire in order to obtain the greatest possible number of layers or windings of metal wire within a limited space and which by reason of its shape will lay to ether very compactly and be arranged so as to insure a clear reception.

It has been found that on account of the magnetic field surrounding each of the several turns of wire in the secondaries of these transformers that an interference is set up between the several turns of wire in the same coil, this interference causing distortion or disagreeable tone quality in the signals received. To overcome this difliculty it has been found of advantage to get the several turns of wire constituting one secondary coil into as small a space as possible in the direction of the axis of the coil. For other reasons it has been found desirable to have the several windings in as small or compact a space as possible and which I find most practicable when making the Wire in ribbon form.

T he invention will be best understood from the consideration of the following detailed description, taken in connection with the accompanylng drawings forming a part of th1s specification, with the further understand- I ing that while the drawings show a practical form of the invention, the latter is not con fined to any strict conformity with the showing of the drawing, but may be changed and modified so long as such changes and modification mark no material departure from the salient features of the invention.

In the drawings Fig. 1 is a diagrammatical view showing an electrical circuit as employed in a radio set, and in connection with which the invention is especially designed to be used;

Fig. 2, illustrates a perspective view of one form of my improved form of radio frequency transformer and illustrating both the primary and secondary coils together with spool, upon which they are mounted;

I Fig. 3 is an enlarged cross section through a portion of an annular transformer including a spool, inner primary coil and outer secondary coil constructed in accordance with my invention; and

Fig. 4 shows a cross sectional view of my improved coil irrespective of a spool and primary wire.

Referring first to Fig. 1, it will be seen that i I have illustrated the usual arrangement of two stages of radio frequency amplification, including three radio frequency transformers, and the usual arrangement of other elements and circuit as is used in various re ceiving sets of the tuned radio frequency type. Upon this Fig. 1, a represents the antennae, B, C and 1) transformers of my improved type, E, F and G tubes connected between the transformers, ground wire and c and (Z and wires leading to and from the B battery whereas wires 6 and f are and wires for the A battery. 7

The invention as applied and shown in enlarged views Figs. 2 and 3, comprises a primary coil H and a secondary coil I mounted upon a suitable spool G of insulating mate rial. This spool is of a ring-like form being comparatively large in circumference and relatively small in cross section, thereby providing for a sufficiently large numbeg ,of wire windings which are compactly applied, as will now be described.

As designed the primary coil which is composed of ordinary covered copper wire may be secured against the inner annular wall of the spool or any convenient means and has one end 7.; extended therefrom for making the necessary connection. 7

The spool, as shown in the Figs. 2 and 3 may also serve to support the secondary coil and for this purpose is provided in its outer periphery with a central relatively deep are nular groove 70 forming substantially parallel side walls or flanges Zto accommodate the secondary coil 2' which, as before stated, is formed of flat or ribbon metal wire, the innermost end ml of said wire being extended through a hole from the bottom of the groove of the spool out through one side for any desired connection and then wound closely upon the spool within the groove, with a strip of insulating material wound between the respective layers, until the desired number of turns.

are provided. Suitable means may be provided for'retaining the secondary windings in position whereupon the outer free end of the wire is carried off to. make the necessary connection. The wire strip for these coils may be slightly narrower than the strip of insulating material and the winding when completemay be covered and sealed with a suitable insulating. material 0. I p

In Fig. 4, I have shown a more condensed form of the invention, the several layers of wire and insulations being enclosed and supported by a covering of parafiine 0 or the like,

and may or may not be supported on a spool.

It will be noted that by the use of fine ribbon wire Wound in the manner described the several layers or" wire are disposed in annular spaced relation to each other in regular ties that a transformer constructed in accordance with my invention, in the manner described, will produce a very much clearer tone, than that which I have been able to, get

i with the commercial types of transformers employing the round insulated metal wire.

This transformer may obviously be used in radio sets in the usual manner, by arranging them approximately at right angles to each other.

Having thus described my invention what- I claim and desire to secure byvLet-ters Pat ent is A radio'frequency transformer comprising a'ring of relatively large internal diameter and having an annular groove relatively wide as compared withthe width of the ring 7 formed in the outer periphery thereof, a secondary coil comprising superposed layers dlsposed within said groove and maintained against lateral movement by the walls thereof, and a primary coil'comprising a single layer of wire disposed side by side arranged against the inner periphery of said ring.

Signed at Bridgeport in the county of Fairfield and State of Connecticut this 3rd day of March, A. D. 1926. V

FRANK L. CAPPS. 

